1. Field of the Invention
The invention relates in general to servicing methods and apparatus, and more specifically to such methods and apparatus for servicing elevator systems.
2. Description of the Prior Art
The control for elevator systems is complex due to the large number of different functions which are controlled, and due to the many different interrelationships between the functions. Each elevator car includes a car controller which includes all necessary control for operating the associated elevator car. A hall call controller receives the floor or hall calls which are registered for elevator service, and this controller resets the calls when they have been serviced. When several elevator cars serve the same floors, a group supervisory controller is usually provided which overrides the per car call-answering strategy built into each car controller, and it causes the elevator cars to answer hall calls according to a predetermined operating strategy designed to more efficiently serve the associated building. A malfunction occurring in one of the controllers may be associated with an elevator car, or it may be a system malfunction which affects all elevator cars.
A malfunction which affects safety usually shuts down immediately the associated car, or cars, and they remain out of service until authorized personnel can determine the cause, correct it, and place the car, or cars, back in service. When the safety relay associated with an elevator car drops to take its associated elevator car out of service, for example, it can be due to any one of a large number of different conditions, all of which have a contact in a serial string of contacts which are connected to the safety relay. Thus, many different functions may have to be checked in order for service personnel to determine the exact cause of the malfunction.
Some malfunctions occur intermittently, and the cause may not be apparent at the time service personnel attempt to determine the cause of a particular malfunction. This is true whether the malfunction causes a car to be taken out of service, or whether the malfunction merely causes a degradation of service while the malfunction persists.
Some malfunctions may not be due to any specific combination of detectable events, because the malfunction may be due to a normal combination which persists for an abnormally short, or an abnormally long, period of time.
Some malfunctions may not be easily detectable by the users of the elevator, or by the building owner, and yet the malfunction may be degrading building service because certain operating strategies are not being properly triggered, for example, in response to building operating conditions.
When it is known that service is being degraded due to an intermittent condition, or other abnormal operating condition which is difficult to isolate, the usual approach is for service personnel to bring a multi-channel strip chart recorder into the building. The various channels of the recorder are connected to suspected control elements. A bulky relay timer system may additionally be brought into the building, and connected to the hall call relay contacts. After a significant period of time, the service personnel report back to the building and sort through the reams of paper processed by the recorder, in the hope of detecting the specific cause of the intermittent or abnormal operating condition.